Delete the now expired postgresql90 ports. Upstream support for
postgresql-9.0.x was declared EoL in September 2015.
Summary:
Remove 9.0 from the list of postgresql versions available in ports
Disconnect postgresql90 ports from the build
Remove postgresql90-pgtcl port
Remove postgresql90-client port
Move the master postgreslXY-plperl makefile to postgresql95-plperl/Makefile.
Adjust include lines in other postgresqlXY-plperl ports

The PostgreSQL Global Development Group announces the beta release of
PostgreSQL 9.2, which will include major increases in performance and
both vertical and horizontal scalability. The PostgreSQL Project asks
all users to download and begin testing 9.2 Beta as soon as possible.
Major performance and scalability advances in this version include:
* Index-only scans, allowing users to avoid inefficient scans of base
tables
* Enhanced read-only workload scaling to 64 cores and over 300,000
queries per second
* Improvements to data write speeds, including group commit
* Reductions in CPU power consumption
* Cascading replication, supporting geographically distributed standby
databases